P17005: Assistive Tablet Case

Imagine RIT

Table of Contents

Problem Statement

Children with Nonverbal Autism often do not have access to tablet-based AAC applications due to their coupled conditions of Sensory Processing Disorder (SPD) and Motor Skill Difficulties. This limited access is the result of inadequate portability for children, reduced operability for the user, and a lack of sensory-friendly materials.

Target User

Our research has indicated that children with Nonverbal Autism tend to be introduced to some form of AAC very early in life, sometimes as soon as 18 months old, though they tend to start with a more low-tech picture exchange, wherein physical pictures of things are passed between conversation partners. Because of this early intervention, our target age-range is 4-7 years old. The following criteria also apply to our target user:

Our Solution

Motormouth enables continuous communication through consistent access to a tablet to utilize the AAC applications available. This device provides a portable and sensory-friendly alternative to traditional tablet cases by way of interchangeable textures and a self-supporting wearable design.
Device Harness

Device Harness


The most obvious feature of this device is the harness, which was designed to carry the tablet while holding it secure against the body. A harness design was chosen over a messenger-bag type because feedback from Subject Matter Experts (SME's) suggested the uneven pressure of a messenger bag might be a deterrent to many children with SPD. The harness features plastic inserts to provide extra rigidity and support which are removable for washing, D-rings for attaching personal items, Velcro closures for easy on/off, and elastic along the belt to provide variable compression and avoid a "too tight" feeling.

The harness holds the tablet on the user's back while not in use, with the screen facing in to prevent damage. The team determined that, at such a young age, the child's back was the only place to store a full-sized tablet without it interfering in the child's movements. A full-sized tablet was also chosen, rather than a smaller size, because of these children often have coupled vision and motor problems, and a smaller tablet would mean smaller icons to have to select, or fewer icons to choose from.

Moving System

To transfer the tablet from the hold-position on the back to a use-position on the front, a track system was designed. A flexible, nylon track is attached to the harness, and a slider mechanism is used to connect the tablet to the track.

Demo of Track and Slider System

Demo of Track and Slider System

Track and Slider

The image above shows the track and slider demo that was at Imagine RIT. This is a scaled up version of what would be on the harness, though the length of the track was held constant. The curved part on the left would be on the back of the harness, and the flat part would wrap around the belt to the front. The slider uses a lever system to create a high amount of friction in one direction in order to lock the tablet in any position on the track, to prevent it from falling or becoming out of the user's control.

Chain and Pulleys

The slider is driven along the track by an embedded cable which is similar to the beaded chain used for window blinds. The beaded chain cable mates at either end with toothed pulleys to prevent the cable from slipping. On the front side of the track (the right end in the image) The pulley is actually two in one. One pulley is much smaller than the other, creating a "geared-down" effect. The cable on the smaller pulley is routed above the track, and a handle is attached at one point. This is the user's input, and the gearing results in a much shorter distance for the user to pull the handle through while still driving the slider along the entire length of the track. In the final version, only the small section of the user's cable will be visible - the section that the handle moves through - to prevent interference with the rest of the cable.

Crossbar System

To provide a hands-free use-position, the tablet is mounted on a crossbar. When not in use, the tablet is folded so that the screen is facing the harness. When the user pulls the tablet around to the front to use, it is pulled up in the crossbar and leaned out at an angle. Small features on the tablet case and the crossbar meet to secure the tablet in the angled position. In this manner, the tablet is self-supported in a use-position on the belt of the harness until it is no longer needed and folded back.

Demo of Crossbar System

Demo of Crossbar System

Tablet Case and Texture Plates

The tablet case is made of durable, impact-resistant material in order to protect the tablet, and has a rectangular form to accommodate the crossbar. The edges of the case are thicker, providing further protection for the electronic device inside. A depression on the back of the tablet makes room for the addition of texture plates, which are interchangeable plates with varying textures attached to provide tactile stimulation to those who use such input for self-regulation. This is common for individuals with SPD, as it can help block out overwhelming stimuli from other sources, such as a noisy room of people.

Customer Requirements

Customer requirements describe the desired end-state of the project, from a customer or user point of view. Because this was a student-proposed project, the requirements were unclear at first. Through talking with Occupational Therapists (OT's) the following "customer requirements" were decided upon.
Customer Requirements

Customer Requirements

Each customer requirement was given an ID (ie CR01) and a short description of the desired function. We connected each CR to a quality requirement (QR) and a test requirement (TR) and included a longer description justifying the need for the feature. Due to time constraints, we were not able to fulfill all customer requirements, and the table-stand feature was put off to be included at a later time.

Engineering/Quality Requirements

Engineering requirements were referred to as "quality requirements" since the team was comprised of more than just engineers. These QR's describe how fulfillment of the customer requirements can be confirmed.
Quality Requirements

Quality Requirements

Similar to the CR's, QR's were each given an ID code (QR01) and a short description of the requirement. For each requirement, the state of the test specimen was also described, since some QR's described a design requirement while others described a requirement of the completed system. Each QR also had a prescribed target value, and a slightly less ideal acceptable value.

Test Plans

The quality requirements above were used to create specific test plans, which laid out the above information and described a sequence of events for each test, as seen in the sample below. Overall, 14 test plans were laid out to test everything from impact resistance and device safety to user satisfaction. Test ID's of the form TR2X indicate that the test is Human Subject Research, approved by the school's IRB.
Example Test Plan

Example Test Plan

The test plan above describes a test to ensure the effectiveness of a grid overlay for improving the accuracy of icon selections. As in the example above, some tests use a qualitative 1-5 scale of measurement, with each integer being distinctly defined. In other tests, a quantitative value is used, as in the calculations shown here for "accuracy" and "improvement."

Testing is scheduled to be completed this summer, in parallel with teammate Christina's Master's thesis project on Autism Access Technology. The tests will be conducted by an OT or other professional in the field, so test plans had to be precise enough for someone outside the team to follow.